Honda U3-X Self-Balancing Unicycle Video

The Honda U3-X is a self-balancing motorized unicycle is a new "personal mobility" technology just announced in Tokyo. It isn't fast - less than four miles per hour - but you can't match its gliding motion. In any direction.

(Honda U3-X like Heinlein's tumblebug)

Science fiction fans may see this as being pretty close to Robert Heinlein's tumblebug from his 1940 novella The Roads Must Roll:

Gaines and Harvey mounted tumblebugs, and kept abreast of the Cadet Captain, some twenty-five yards behind the leading wave. It had been a long time since the Chief Engineer had ridden one of these silly-looking little vehicles, and he felt awkward. A tumblebug does not give a man dignity, since it is about the size and shape of a kitchen stool, gyro-stabilized on a single wheel.
(Read more about (and see a picture of) Heinlein's tumblebug)